There are some additional game perimeters I wish to use for my map, but I'm not quite sure how to add them. What exactly would I need to type in to add the commands -staticproppolys, -textureshadows and -staticproplighting?

Basically they mostly open and close correctly, but if I press a door that is currently opening/closing, it starts rotating 360±90º.
I've tried putting doors without anything around it, moving its origin, creating new ones from scratch, but I can't figure this out.

However, I have seen this behaviour a few times recently in other maps, which makes me believe it's a new problem with GMod/Source and not the actual map?

Basically they mostly open and close correctly, but if I press a door that is currently opening/closing, it starts rotating 360±90º.
I've tried putting doors without anything around it, moving its origin, creating new ones from scratch, but I can't figure this out.

However, I have seen this behaviour a few times recently in other maps, which makes me believe it's a new problem with GMod/Source and not the actual map?

It usually does this when you map for CSS, since your mapping for Gmod, its all linked.

This may float your boat. Quick Google search of "save file in multiple directories" brought that up, but I'm sure if that doesn't work you can probably find something else. This seems like a generic problem someone should have ran into and decided to cover.

How can I increase the size of the Visgroup window on the Hammer sidebar? I saw some guy has Visgroups quite long. As you can see, I'd like to stretch it all the way down, so I can see all my Visgroups clearly, I've got a bunch.

Is there a way to make good-looking, dusty rooms?
I want to make an apartment, already abandoned for many years, sunlight shining thorugh the windows.
I already added func_dustmotes, but func_dustcloud looks way to ugly.
Is there another "dust-like" effect I could use?

That worked like a charm, thanks man! And yeah, that's a perfect setup you got, but, I'm missing an extra monitor :P Sold it away a while ago, was an oldish 19" LCD. I may buy an extra one at some point again, I'll see.

Another thing you should do is fix the fact that there's more than 4(?) different colors of light on a brush somewhere

I forget how to turn off detail sprites though... maybe look up a tutorial on how to turn them on and then just work backwards

4 differently named lights touching the same brushface. It has nothing to do with colour, as you could have hundreds of lights named the same with different colours and it would work. It's only when you have too many that it'll complain.

I'm sort of asking the same thing. Here's a room I made. I like the color the light is giving off in the room, but it just doesn't "pop". It just feels like it's missing something, the way the light is cast makes everything look a bit stale to me. Would sprites for each fluorescent light fixture be beneficial (right?)? I know that isn't the full the solution though, it's the lighting itself. I know it's missing SOMETHING to make it a bit more atmospheric, but I just don't know what that could be. Any ideas?

That looks full-bright, just orange. It also does not match the light-texture in any way. What are you using for the lighting? Use light_spots + sprites.

I'm using a light_spot with a wide angle. Yeah, it looks pretty orange, and that's the problem. It looks to much of a uniform light, bland and stuff. Should I try reducing the angle and possibly the light a bit? Here's the brightness I'm using for them along with the angles... (And there's one light_spot in the middle of each of the florescent light fixtures)